The KWP2000 protocol has turn into a de facto customary in automotive diagnostic functions. It’s standardized as ISO 14230-3. KWP2000 describes the implementation of assorted diagnostic companies you’ll be able to accethrough the protocol. You may run KWP2000 on a number of transport layers resembling Okay-line (serial) or CAN.

Transport Protocol

As KWP2000 makes use of messages of variable byte lengths, a transport protocol is critical on layers with solely a effectively outlined (quick) message size, resembling CAN. The transport protocol splits an extended KWP2000 message into items that may be transferred over the community and reassembles these items to recuperate the unique message.

KWP2000 runs on CAN on numerous transport protocols resembling ISO TP (ISO 15765-2), TP 1.6, TP 2. 0 (Volkswagen), and SAE J1939-21. For KWP2000, the Automotive Diagnostic Command Set helps solely the ISO TP (standardized in ISO 15765-2) and manufacturer-specific VW TP 2.Zero transport protocols.

Diagnostic Providers

The diagnostic companies obtainable in KWP2000 are grouped in purposeful models and recognized by a one-byte code (ServiceId). The usual doesn’t outline all codes; for some codes, the usual refers to different SAE or ISO requirements, and a few are reserved for manufacturer-specific extensions. The Automotive Diagnostic Command Set helps the next companies:

• Diagnostic Administration

• Information Transmission

• Saved Information Transmission (Diagnostic Hassle Codes)

• Enter/Output Management

• Distant Activation of Routine

Add/Obtain and Prolonged companies will not be a part of the Automotive Diagnostic Command Set.

Diagnostic Service Format

Diagnostic companies have a typical message format. Every service defines a Request Message, Constructive Response Message, and Adverse Response Message. The Request Message has the ServiceId as first byte, plus extra service-defined parameters. The Constructive Response Message has an echo of the ServiceId with bit 6 set as first byte, plus the service-defined response parameters.

The Adverse Response Message is often a three-byte message: it has the Adverse Response ServiceId as first byte, an echo of the unique ServiceId as second byte, and a ResponseCode as third byte. The one exception to this format is the adverse response to an EscapeCode service; right here, the third byte is an echo of the user-defined service code, and the fourth byte is the ResponseCode. The KWP2000 customary partly defines the ResponseCodes, however there may be room left for manufacturer-specific extensions. For a number of the ResponseCodes, KWP2000 defines an error dealing with process. As a result of each constructive and adverse responses have an echo of the requested service, you’ll be able to all the time assign the responses to their corresponding request.

Join/Disconnect

KWP2000 expects a diagnostic session to be began with StartDiagnosticSession and terminated with StopDiagnosticSession. Nevertheless, StartDiagnosticSession has a DiagnosticMode parameter that determines the diagnostic session sort. Relying on this kind, the ECU could or could not assist different diagnostic companies, or function in a restricted mode the place not all ECU features can be found. The DiagnosticMode parameter values are producer particular and never outlined in the usual. For a diagnostic session to stay lively, it should execute the TesterPresent service periodically if no different service is executed. If the TesterPresent service is lacking for a sure time period, the diagnostic session is terminated, and the ECU returns to regular operation mode.

GetSeed/Unlock

A GetSeed/Unlock mechanism could defend some diagnostic companies. Nevertheless, the relevant companies are left to the producer and never outlined by the usual.You may execute the GetSeed/Unlock mechanism via the SecurityAccess service. This defines a number of ranges of safety, however the producer assigns these ranges to sure companies.

Learn/Write Reminiscence

Use the Learn/WriteMemoryByAddress companies to add/obtain knowledge to sure reminiscence addresses on an ECU. The tackle is a three-byte amount in KWP2000 and a five-byte amount (four-byte tackle and one-byte extension) within the calibration protocols. The Add/Obtain purposeful unit companies are extremely producer particular and never effectively outlined in the usual, so they don’t seem to be a great way to supply a common add/obtain mechanism.

Measurements

Use the ReadDataByLocal/CommonIdentifier companies to entry ECU knowledge in a method just like a DAQ checklist. A Native/CommonIdentifier describes a listing of ECU portions which can be then transferred from the ECU to the tester. The switch could be both single worth or periodic, with a gradual, medium, or quick switch price. The switch charges are producer particular; you should utilize the SetDataRates service to set them, however this setting is producer particular. The Automotive Diagnostic Command Set helps single-point measurements.

Diagnostic Hassle Codes

A significant diagnostic function is the readout of Diagnostic Hassle Codes (DTCs). KWP2000 defines a number of companies that entry DTCs primarily based on their group or standing.

Enter/Output Management

KWP2000 defines companies to switch inner or exterior ECU indicators. One instance is redirecting ECU sensor inputs to stimulated indicators. The management parameters of those instructions are producer particular and never outlined in the usual.

Distant Activation of a Routine

These companies are just like the ActionService and DiagService features of CCP. You may invoke an ECU inner routine recognized by a Native/CommonIdentifier or a reminiscence tackle. Opposite to the CCP case, execution of this routine could be asynchronous; that’s, there are separate Begin, Cease, and RequestResult companies. The management parameters of those instructions are producer particular and never outlined in the usual.

Exterior References

For extra details about the KWP2000 Normal, confer with the ISO 14230-Three customary.



Source by Amos Huang